Field of the Invention
The present invention relates to an organic electroluminescent illuminating device including a driving unit and a flexible surface light-emitting unit provided with an organic electroluminescent element.
Description of Related Art
In recent years, illuminating devices provided with light sources composed of a surface light-emitting unit including an organic electroluminescent element (hereinafter referred to as “organic EL element”) have attracted attention. A common organic EL element is composed of an anode, a cathode, and an organic functioning layer including a light-emitting sublayer (a thin film of an organic compound including a light-emitting organic compound), the organic layer being disposed between the anode and the cathode. The organic EL element is driven by current flowing therethrough via the anode and the cathode to emit light and is used in decorative lights, signal light sources, light-emitting posters, illuminating devices, and other devices.
New applications of illuminating devices including organic electroluminescent elements have recently been required to provide a room light exhibiting sufficient flexibility, three-dimensional appearance, and a sense of depth, which are advantageous for dramatic and decorative impact, and demonstrating the dramatic and decorative impact inherent in the properties of the organic electroluminescent elements.
To meet such a requirement, U.S. Patent application publication. No. 2013/0044487 discloses an illuminating device including a flexible organic electroluminescent element with two ends connected to rotatable supports to dynamically change the state of the bend, although it does not disclose a specific method of driving an illuminating device including a flexible organic electroluminescent element. Unfortunately, in this structure, the two ends of the flexible rectangle organic electroluminescent element are each fixed to two supports, so that the organic electroluminescent element cannot be smoothly moved, resulting in insufficient dramatic or decorative impact.
Japanese Unexamined Patent Application Publication Nos. 2010-003547 and 2012-256525 each disclose an illuminating device which is openable like petals, includes a plurality of circularly-disposed surface light-emitting units, parts of which are connected to a driving device. An accompanying photosensor detects the intensity of external light such that the petal-like surface light-emitting units open in the dark. Unfortunately, in this structure, the surface light-emitting units are composed of an inflexible or rigid material to form a petal-like shape; hence, the organic electroluminescent element cannot be smoothly moved, resulting in insufficient dramatic or decorative impact.
No illuminating devices have yet appeared which include surface light-emitting units provided with flexible organic electroluminescent units having various shapes and movable naturally and smoothly, resulting in insufficient dramatic or decorative impact. An attractive illuminating device free from such problems is therefore required.